This invention relates to the use of converted starches capable of forming gels as fat- and/or oil-replacements in various foodstuffs.
Over the past few years, heavy emphasis has been placed on the development of fat and/or oil-replacement products for foodstuffs high in fat or oil, such as salad dressings, ice cream and the like. Increased consumer awareness of the calorie content of foods and the recent sharp increase in vegetable oil prices have intensified interest in such replacements.
It is known that most undegraded cereal starches yield dimensionally stable puddings with gel-like properties after gelatinization in water at concentrations of about 5-12% by weight. These same gelling properties are found in potato starches (so-called potato starch flours) which have been slightly modified by suitable chemical treatment.
The main disadvantage of the above starches is the fact that their gels in water are not stable at low temperatures and/or for prolonged storage periods. The gels undergo irreversible conversions on freezing, and the starch has, after defrosting, the form of a water-insoluble spongy mass. When the gels are stored, the high molecular starch components irreversibly associate, forming hydrogen bridge bonds, and the consistency changes to such an extent that the gel becomes hard and repels water. Another disadvantage of native starches is the fact that their aqueous dispersions are too high in viscosity and/or their gel-like preparations have a typical sticky-pasty consistency. They are not suitable for use in foodstuffs that must maintain their shape after spreading or stirring.
Derivatized starches containing functional groups (e.g. carboxymethyl starch or starch phosphates) suffer from the disadvantage that the consistency of their gels in water depends to a great extent on the pH-value. In addition, they are greatly influenced by salts.
The above shortcomings have been overcome by the use of starch hydrolysis-products (SHP) having specific dextrose equivalents (DE), i.e. at least 5% but below 25%, for the formation with water of thermoreversible secondary valence gels (see U.S. Pat. No. 3,962,465 issued June 8, 1976 to M. Richter et al.). These products, also known by the name malto-dextrins, are characterized, not only in terms of their DE, their formation with water of white glossy thermoreversible gels having a neutral taste, a pasty to cutting hard consistency, and a stability to freezing and defrosting, but also by the step-wise enzyme conversion used for their preparation.
As disclosed in U.S. Pat. No. 3,986,890 issued Oct. 19, 1976 to M. Richter et al., SHP-containing mixtures having an average DE of 5-10 also form thermoreversible gels. The admixtures are prepared by combining starch products whose combination have the required DE, the starch products having different degrees of polymerization and differing from each other by at least 10 times, with each of the starch products being branched and at least one being the starch hydrolysis product.
The gels are white, glossy, and thermoreversible. They are stable to freezing and defrosting and have a consistency which can vary from pasty to cutting hard depending upon the amount of water in the gel.
While the above SHP products are satisfactory, their preparation is not convenient. The preparation is carried out by suspending the starch or water-soluble starch derivative in a concentration of 15-50% by weight and the starch-hydrolyzing enzyme bacterial alpha-amylase in a concentration effective to produce the SHP. The pH of the suspension is adjusted to about 7 and the suspension is then heated from 55.degree. to 70.degree. C. in a period of 5-30 minutes, then from 70.degree. to 95.degree.-100.degree. C. in a period of 5-20 minutes, and finally maintained at the latter temperature for 5-20 minutes, whereby a precipitant is formed. The precipitant is separated from the supernatant liquid which is a solution of SHP. SHP may be recovered in solid form by dehydrating the solution. This procedure is not convenient because it requires constant monitoring.
It is therefore desirable to prepare converted (i.e. hydrolyzed) starches having comparable gelling properties but made using simpler procedures that do not require constant monitoring and that preferably permit recovery of the converted starches by more economical procedures.